High speed keying



Jun@ 4, 1935.

L. L. YOUNG HIGH SPEED KEYING Filed Nov. 5, 1931 SSheets-Sheet 2 INVENTOR LLOYD b21 6 BY ATTORNEY Filed Nov.

5, 1931 S Sheets-Sheet 3 6 Rw m N O R E w V A W LLOYD BY Lg Patented June 4, 1935 UNITED STATES HIGH SPEED KEYING Lloyd L. Young, Patchogue, N. Y., assignor to Radio Corporationof America, a corporation.

of Delaware Application November 5, 1931, Serial No. 573,057

9. Claims.

This invention relates to transmitter keying means and more in particular to means cooperating with a signal perforated tape to convert at high speed the perforations therein into electrical energy impulses, the variations of which are representative of the signal on the tape.

General arrangements, known heretofore in the prior art for keying a tape, comprise contact members which make and break in accordance with the perforations in the tape. The tape gen erally includes a continuous row of uniformly spaced tractions or center hole perforations in addition to the rows of signal perforations on each side of the center row. The tape is passed over or adjacent the keying members which cooperate with a contact member to complete a circuit through the perforations, thereby changing the signal perforations into electrical energy impulses, the spacing or intensity of which are characteristic of the signal perforations.

The arrangements known heretofore are inherently subject to many disadvantages, as, for instance, the electrical contacts are destroyed due to the voltage and current carried thereby.

. Moreover, considerable difficulty is encountered in providing contacts light enough to operate at high speed and yet sturdy enough to stand up under the voltages involved in keying the transmitter. Another disadvantage, one which is very serious, is that the speed at which the tape can be keyed is limited by the; size and weight of the keying members and the rate at which they can be reversed in motion.

In general the object of the present invention is to provide a novel keying means by means of which all of the above disadvantages may be overcome.

More in detail, one object of this invention is to provide a high speed transmitter in which no electrical contacts are used.

Another object of this invention is to provide a high speed tape keying means which has a minimum of moving parts, and which parts move a small amount and at a slow speed.

Still another object of this invention is to provide a tape transmitter in which the electrical impulse resulting from the keying operation is purely characteristic of the signal and is in no manner affected by the speed of the transmitter. A further object of this invention is to provide a high speed transmitter which is eihcient, accurate and operable at speeds unknown before, but which is subject to no dangerous voltages.

Another object of the present invention is to provide a novel keying means as described above,

which may be used in combination with various translating circuits readily.

Numerous other advantages will appear from the specification and from the drawings.

Briefly, the above objects and advantages are 5 obtained in accordance with thepresentinvention by'providing a magnetic circuit, the reluctance of which is varied at signal frequency. The circuit is free of contact making or break-j ing members. The changes or variations in rere luctance .of the circuit are utilized in a novel manner to produce in circuits associated therewith voltage variations corresponding to the variations in reluctance in said magnetic circuit thereto. The voltage variations may be utilized 15 in any desired manner, as, for instance, to control the input circuit of a thermionic relay stage.

More, in particular, the above objects are attained by providing a magnetic circuit or magnetic circuits which include a variable air gap,; 2t the length of which is caused to vary at signal frequency. 'Magnetizing current is supplied from a source associated with said magnetic circuit. The reluctance of said circuitis determined by the length of the air gap therein, while the in- 2 51- tensity of the current in said circuit is deter-- mined by the reluctance thereof; A winding associated with said magnetic circuit will have en-- ergy induced therein which will vary as the reluctance of said magnetic circuit is varied. This 3o. winding may be associated with a utilizing circuit.

The magnetic circuit includes a variable air gap comprising a plunger mounted adjacent the tape and an armature cooperating therewith so that relative motion between the tape and the plunger and armature causes theplunger to align with perforations in the tape so that it may pass, through said tape under the action of a spring and approach said armature, thereby varying the 40 length of the air gap in the magnetic circuit which is completed through a conductive path connected at one end with said plunger and at the other end with said tape. 7

In a modification an alternating current winding, or windings, may serve to energize the magnetic circuit and to act as a utilizing circuit. In this modification a change in the length of the air gap in said magnetic circuit causesa change in the reactance of said winding, or windings, and hence a change in the voltage across said winding, orwindings, which may be utilized in a work circuit, as, for instance, to actuate a ther mionic relay.

An-advantage. to be gained by this arrangement is that the speed of keying could not, under any circumstances, influence the voltages representative of the signal perforations.

A more complete understanding of the invention Will be had from the specification and therefrom when read in connection with the drawings in whichlike reference characters indicate like parts and in which:

Figure 1 shows partly in section a high speed keying means arranged in accordance with the present invention;

Figure 2 shows a side view of the arrangement of Figure 1, parts being omitted for clearness;

Figure 3 shows a top view of the tape transmitter of Figure 1;

Figure 4 shows, merely for purposes of illustration, a utilization circuit by means of which the variations in reluctance of the magnetic circuit produced by the transmitter of the prior figures may be used to produce voltage oscillations;

Figure 5 shows a modification of the arrangement of Figures 1, 2 and 3;

Figure 5a shows diagrammatically. one form of circuit to utilize the voltage variations produced by the arrangement of Figure 5, while Figures 6 and 7 show preferred forms of utilization circuits associated with applicants novel keying means.

Referring to the drawings, and in particular to Figure 1 thereof, a wheel W is mounted for rotation on a shaft 6, shown partly in section. The wheel W comprises a body member X having a groove on each face adjacent the periphery in which a pair of metallic rings 22 and b may be retained. Themetallic rings 1) and 1) form part of a magnetic circuit of varying reluctance, as will appear more in detail hereinafter. Adjacent the periphery of the wheel W is a pair of magnetic yoke members a and a, one pole of each of which magnets approaches the rings b and b. The other pole of each of the magnets a and a are disposed adjacent armature members H and H. The armature members H and H extend above and adjacent the periphery of the wheel W as shown. The rings b and b have a plurality of openings in the periphery thereof, as shown, in which are mounted a plurality of plungers c and c, biased by spring members I and 8, bearing at one end on b and b respectively and at the other end on shoulders I and 8 on pins 0 and 0 respectively, to normally move said pins radially away from the center of the wheel W. The outer ends of the plungers c and 0 pass through openings in the flange of wheel W, as shown in Figure 1.

A plurality of traction pins J are fastened around the periphery of W and spaced thereon an amount equal to the spacing of the traction holes in the tape. During operation the pins J enter the center row of perforations in the tape 1 and on rotation of the wheel W pull the tape f along'over the wheel. The springs 1 and 8 on the plungers c and c normally tend to move the plungers c and 0 toward the armatures H and H. The tape 1 keeps the plungers c and c from moving toward H or H unless a perforation is passing over the plunger.- When a perforation passes over the plunger the plunger is forced by its spring through said perforations toward the armature H or H, This varies the distance between the plunger and the armature, and thereby varies the reluctance of the magnetic circuit. A source of direct current 8 is connected with windings d and d, mounted on the yokes a, and.

a, to produce a magnetic field in the magnetic circuit. A second pair of windings e and e are mounted on the yokes a and a for a purpose which will appear more in detail hereinafter.

, In operation the plungers c and c in the vertical positions complete magnetic circuits through the yokes a and a, the rings 1) and b and the armatures H and H. Winding 01 carries magnetizing current from the direct current source 8. Any change in the reluctance of the magnetic circuits a, b, c and H or a, b, c and H will cause a change in the flux density in said circuit and thereby induce a voltage across windings e and e. The tape 1 is passed over the wheel W. As the wheel W is rotated the traction pins J pull the transmitting tape ,f over the periphery of the wheel W. Plungers c and c are either re- .tained in normal position by the tape or protrude through tape perforations so that the air gap between the plunger 0 and H or c and H decreases so that the reluctance of the magneticcircuit is minimum when the plungers are in the extendedposition and maximum when the plungers are restrained by the tape, thereby maintaining a large air gap between 0 and H or c and H.

'As the wheel W is rotated further the plunger 0 or 0 passes from under the armature H, thus increasing the air gap in the magnetic circuit, decreasing the flux density in said circuit and producing in e and e voltage changes. As the wheel continues torotate the plunger 0 is disengaged from the tape.

When there is no perforation for a plunger 0 or c to pass through the plunger is held in a depressed position by the tape, thus making a larger air gap so that the flux density will be substantially the same as when the position of the wheel W relative to the armature, H, is such that the armature is equidistant from two adjacent plungers in extended position, there will be no voltage induced across e or e.

Since one set of plungers function through the on perforations of the tape and the other set function through the off perforations, by adjusting' the positions of the two armatures H relative to their respective plungers c and c to give proper bias the voltage impulses produced in windings e and e may be used in communications.

To facilitate starting the tape in the transmitter the armatures H and H are carried in an insulating shoe K supported on a hinged member IE! fixed at II, as shown in Figure 2. The shoe K may be lifted on the hinged member l0 while the tape J is being placed in position. The shoev K is then lowered into place where a suitable they bear on the yoke members a and (1 respec-' tively during operation.

The potential variations in windings e and 2 may be utilized in any manner known in the art to operate a printing relay, or to energize the input circuits of thermionic relays, or to energize the input circuits of a thermionic trans-- mitter.

One manner in which the potential variations appearing in e and e may be utilized is shown in Figure 4. Windings d and d on the same cores with windings e and e respectively are energized as shown from a source 8 (see Figure 1) to produce a predetermined flux density in Normally the weight of age applied to tube from the biasing battery the cores. Operation of the keying means as described in connection with Figure 1 changes the reluctance of the path and'con'scquently the flux density at signal frequency. This results in a change in the impedance of the inductances e and e and results in voltage changes across the terminals thereof. In Figure 4- these potential changes appear across the inductances e and e". A pair of thermionic tubes I2 and i3 have their filament circuits connected together and to terminals 3, t of windings e and e respectively.

The terminals 2 of windings e and e are con nected togetherthrough resistances I5, I6 and to the control electrodes of tubes I2, 93. The output electrodes of tubes I2 and I3 are connected through an inductance which may be coupled in any manner as, for instance, inductively to any utilization circuit, termed in this case a tripping circuit; The utilization circuit may be an antenna connected to a transmitter or to any known load circuit.

A simplified form of the invention is shown in Figure 5. n this modification the magnetic circuits are as shown in the prior arrangement.

Here, however, the field of the magnetic circuit is produced by alternating current from a source 28 connected to windings d and (1' associated with yo-kes a and a respectively. Keying here produces changes of reluctance in the magnetic circuit the same as in Figure 1. Here, however, the changes in reluctance in the magnetic circuit at signal frequency produces corresponding changes in impedance of the alternating current windings d and d. This obviates the necessity of a separate source of direct current for producing the magnetic field.

These changes in impedance obtained by the arrangement of Fig. 5, may be used in the same manner as said changes obtained by the arrangement of Figures 1 to 3 as illustrated in Figure 4, and may be utilized, as indicated in Figure a, to actuate a thermionic relay. The windings d d of Figure 5 in practice replace the windings e 6 respectively, of the circuit of Figure 4. The utilization circuit for the arrangement of Figure 5. as shown in Figure 5a, is otherwise the same as that of Figure 4 and needs no further illustration here.

An arrangement for utilizing the potential variations at keying frequency arising across the inductances in the magnetic circuit of any of the modifications described above has been illustrated more in detail in Figure 6. Referring in particular to Figure 6, tubes A and B are biased by a source not shown to a point near cut off so that rectification of currents representative of the keying potentials takes place in the anode cathode circuit of these tubes. When the impedance or inductance of L1 in one of the magnetic circuit-s equals the impedance or inductance of the inductance L2 in the other magnetic circuit the alternating current applied from I8 to the circuit including the resistances I5 and I 6 and said aforementioned inductances is balanced and both tubes A and B have the same excitation and draw the same amount of current from the anode source not shown. If the impedance of L1 is less than. the impedance of L2 the alternating current voltage drop in resistance I5 causes an unbalance in excitation of the tubes A and B. The tube.

A draws greater current causing direct current to flow from the plate of B to the plate of A. This results in a corresponding drop in polarity across the resistance R3. This impulse or drop in potential gives an increase in the biasing voltoftube C increases; the plate of tube C is transferred through the re- 20. through resistance 2!, and a decrease in the biasing voltage applied to the control electrode of the tube D of the polarized'relay through resistance 22. The tube D draws current.

the grid 24 of C is connected through a resistance 25, as shown, to the plate 23 of D, the tube'C is biased to cut oif and voltage on the plate 26 This increase in potential on sistance 21, .as shown, to the control electrode 28 of tube D increasing the biasing potential on said elements so that tube D becomes strongly conductive and continues conductive until the impedance of L2 becomes less than the impedance of L1. This change in impedance causes the combination to trip in the opposite direction and the tube'C becomes strongly conductive. Thus one tube can carry the marking current impulses and the other tube can carry the spacing current impulses. Since the tripping circuit, as briefly described above, has been described and claimed in application Serial No. 364,831, filed May 21, 1929 by J. L. Finch, and application Serial No. 380,447, filed July 23, 1929, by J. L. Finch, and forms no part of the present invention, a detailed description thereof is thought unnecessary in this application. 7

Another novel manner in which the novel keying device of the present invention may be used is shown in Figure 7. In Figure '7 the inductances L1, L2 of the keyer I9 are connected, as shown more in detail in Figure 6, with a utilizing circuit I which comprises the source of alternating cur rent potential I 8 and the resistances i5 and of Figure 6. The output of the utilizing circuit in I is fed to a suitable amplifier and polarized vacuum tube relay 2, and from thence to an an-- plifier 3. The output of amplifier 3 is fed to a modulator t and from the modulator 4 to a frequency doubler 6. High frequency currents are generated at 5 and set up in 4 to be modulated by the keying impulses impressed thereon from 3. The frequency doubler 6 supplies energy to an amplifier 1 which is connected through trans mission line 8 to an antenna 9 from which the carrier frequencies originating at 5 after being modulated at signal frequency and doubled in 6 are amplified and radiated.

Having thus described my invention and the operation thereof, what I claim is:

1. The combination of a transmitter tape having signal perforations therein and an electromagnetic circuit, of plungers or pins in said circuit cooperating with said perforations in said tape to change the reluctance or reactance in said electromagnetic circuit.

2. The combination of a radio transmitter including, means for starting and stopping the operation thereof, a signal perforated tape, a magnetic circuit of variable reluctance, means cooperating with said perforated tape and with said circuit for varying the reluctance of said circuit in accordance with the perforations in said tape, and means responsive to variations in the reluctance of said circuit to actuate the means for starting and stopping the operation of said radio transmitter.

3. The combination of a transmitter tape having signal perforations therein, an electromagnetic circuit, an oscillation generator, and a frequency multiplier coupled with said oscillation generator, of plungers or pins in said electromagnetic circuit cooperating with perforations in Voltage on the plate 23' of the tube D decreases and, since said tape to change, the reluctance of said electromagnetic circuit, and a device for controlling the operation of said oscillator in accordance with the changes in the reluctance of said electromagnetic circuit.

4. The combination of a transmitter tape having signal perforations therein, an electromagnetic circuit, and an oscillation generator, of plungers or pins in said circuit cooperating with said perforations in said tape to change the reluctance of said electromagnetic circuit, a thermionic amplifier having its input electrodes coupled to saidelectromagnetic circuit, a thermionic relay having a plurality of degrees of electrical stability, and circuits for coupling the input electrodes of said relay to the output electrodes of said amplifier and the output electrodes of said relay to said oscillation generator,

5. In high frequency telegraphy systems, a high frequency oscillator and means for keying said oscillator at signal frequency comprising a magnetic circuit, said magnetic circuit including a variable air gap, means for varying the length of said air gap at signal frequency, a pair of symmetrical inductances located in the field of said magnetic circuit, resistances connected in series with said inductances, a pair of thermionic tubes having their control electrodes connected to terminals of said resistances, and a connection between the output electrodes of said thermionic tubes and said high frequency oscillation generator.

6. High speed keying means to be used with a tape transmitter comprising, a keying wheel having a portion of a plurality of magnetic circuits on the periphery thereof, a yoke member mounted adjacent the periphery of said wheel, and adapted to complete said circuits successively upon rotation of said wheel, a spring pressed plunger in each of said portions of circuits, said plunger being adapted to alter the reluctance of said circuit, means for passing a tape over the periphery of said wheel, an inductance associated with said magnetic circuits, and a thermionic relay tube having its input electrodes connected with said inductance.

7. High speed keying means to be used with a tape transmitter comprising a keying wheel having a portion of a plurality of magnetic circuits on the periphery thereof, a yoke member mounted adjacent the periphery of said wheel and adapted to complete said circuits successively upon rotation of said wheel, a spring pressed plunger in each of said portions of circuits, said plunger being adapted to alter the reluctance of said circuit, and means for pulling said tape over the periphery of said wheel.

8. High speed keying means to be used with a tape transmitter comprising a keying wheel having portions of a plurality of magnetic circuits on the periphery thereof, a yoke member mounted adjacent the peripheries of said wheel and adapted to complete said circuits successively upon rotation of said Wheel, a spring pressed plunger carried by said wheel in each of said circuits, said plunger being adapted to alter the reluctance of said circuit, and means for passing said tape over the periphery of said wheel, whereby said spring pressed plungers cooperate with said tape and tape perforations to vary the length of said air gap at signal frequency.

9. High speed keying means comprising, a keying wheel having a plurality of incompleted magnetic circuits on the periphery thereof, a metallic yoke member mounted on a pivot adjacent the periphery of said wheel, said yoke member, when positioned adjacent said wheel completing said magnetic circuits successfully upon rotation of said wheel, means for rotating said wheel, a spring pressed plunger in each of said incompleted magnetic circuits, said plunger being movable toward and from said yoke member to alter the length of the air gap in the magnetic circuit completed by said yoke member and the magnetic circuit adjacent thereto to alter the reluctance of said completed circuit, means for passing a tape over the periphery of said wheel, and a utilization circuit energized by said magnetic circuits as they are completed.

LLOYD L. YOUNG. 

